Roku Ultra LT not working on TV

It's a fairly old, small flat screen TV. What always, normally, happens with this TV- when I use the remote to power up- first the TV comes on and it'll show at the lower right, "INPUT 4". That's the one that works with the Roku. Then I click on the remote again (in the middle), then I normally would see the light on the Roku come on, then within a few seconds I'll see the main menu. Worked perfect for 4 years. Now, I'll see the INPUT 4 on the TV and the ROKU light actually stays on but nothing happens. When I first noticed this problem, that light was blinking with nothing happening. Now it just stays on. I've tried unplugging it then plugging it back on - but it continues with the same problem. My main TV always works differently, like it's supposed to. When I power up the ROKU, the TV automatically comes on. I haven't tried the problem ROKU on my other TV, I'm a bit hesitant to do this because I don't want my main TV to get messed up- not sure that might happen- but over the decades with personal computers, I've seen how easily you can mess up a system by tinkering. Including a photo won't add anything that I didn't say above. I'll repeat, the TV will just show "INPUT 4" while the ROKU light just stays on but the connection doesn't happen- I suspect the ROKU is deceased. Is there a way to truly reboot the ROKU other than unplugging? If that's possible I'd like to try it.